An international team co-led by Ikerbasque Research Professor Alejandro J. Müller (POLYMAT–University of the Basque Country, UPV/EHU) and Professor Nikos Hadjichristidis (KAUST, Saudi Arabia) has demonstrated that a polymer made of five distinct and potentially crystallizable blocks can self-organize into an unprecedented internal structure. The study, published in Nature Communications, highlights the contributions of Eider Matxinandiarena, first author of the paper, and Ricardo A. Pérez-Camargo, both researchers at POLYMAT-UPV/EHU.
The material investigated is a quintopolymer—composed of five blocks: polyethylene (PE), poly(ethylene oxide) (PEO), poly(ε-caprolactone) (PCL), poly(L-lactide) (PLLA), and polyglycolide (PGA). All are biocompatible, and three of them (PCL, PLLA, PGA) are biodegradable. Integrating these five blocks into a single spherulite makes it possible to achieve multiple functions in a controlled manner.
Its potential applications include the development of new materials for:
- Regenerative medicine: Designing tissue engineering scaffolds that degrade stepwise, initially providing mechanical support and later transitioning into softer phases that promote regeneration.
- Controlled drug delivery: Creating systems in which each block acts as a compartment with a different degradation rate, enabling the timed release of therapeutics
- Advanced technologies: Developing materials with tunable mechanical, thermal, or optical properties thanks to hierarchical control over their structure.
The work was published in one of the world’s most prestigious scientific journals thanks to the rigor and precision with which crystal formation was measured. This analysis required advanced characterization techniques available at UPV/EHU laboratories, the ALBA synchrotron, and the University of Zaragoza, since the crystals formed are about one million times smaller than those of a snowflake. The team determined that crystallization occurs sequentially and hierarchically: PGA → PLLA → PE → PCL → PEO
Each block crystallizes on the structure created by the previous one, building the material layer by layer. This hierarchical control enables precise modulation not only of which segment crystallizes, but also how, when, and where—an essential strategy for designing materials with advanced functional properties.
The spherulites exhibit the characteristic optical pattern of a positive Maltese cross, indicating that the polymer chains orient themselves from the center outward, like spokes of a wheel. This radial organization ensures the continuity of all phases, despite their chemical differences.
A strategic international collaboration
This work is part of several international scientific collaborations, including the European POCTEFA AcroBioPlast project, focused on new biopolymers for biomedical applications (poctefa-acrobioplast.com).
Reference
Matxinandiarena, E.; Pérez-Camargo, R. A.; Sebastián, V.; Zhang, P.; Ladelta, V.; Hadjichristidis, N.; Müller, A. J. (2025). Can five chemically different lamellar crystals self-assemble in a single spherulite? Nature Communications, 16, 9873. https://doi.org/10.1038/s41467-025-64845-6
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